: Using an unsupported OS like iOS 7.1.2 leaves your device vulnerable to malware, as Apple stopped providing security patches for this version years ago.
For users of the iPhone 4—the last device to support iOS 7.1.2—official access to WhatsApp has been disconnected since . This means you cannot download the official app from the App Store, create new accounts, or re-verify existing ones on this firmware. The Reality of Legacy Support whatsapp ipa for ios 7.1.2
: Even if you have an older version of the app installed, WhatsApp's servers now expect newer security handshakes that iOS 7.1.2 simply cannot perform. Potential (But Risky) Workarounds : Using an unsupported OS like iOS 7